Catalytic enantioselective decarboxylative protonation

Journal of the American Chemical Society

Volumn 128, Issue 35, 2006, Pages 11348-11349

  Mohr, Justin T ^a   Nishimata, Toyoki ^a   Behenna, Douglas C ^a   Stoltz, Brian M ^a  

^a California Institute of Technology   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON; ESTER; KETONE; LIGAND; METAL COMPLEX; OXAZOLINE DERIVATIVE; PALLADIUM COMPLEX; PHOSPHINE DERIVATIVE;

ARTICLE; CATALYSIS; CHEMICAL REACTION; CHEMICAL STRUCTURE; CHIRALITY; DECARBOXYLATION; ENANTIOSELECTIVITY; GAS CHROMATOGRAPHY; HIGH PERFORMANCE LIQUID CHROMATOGRAPHY; PROTON TRANSPORT; SYNTHESIS;

CATALYSIS; DECARBOXYLATION; KETONES; MOLECULAR STRUCTURE; PALLADIUM; PROTONS; SOLVENTS; STEREOISOMERISM;

EID: 33748361789     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja063335a     Document Type: Article

References (20)

1. For reviews of enantioselective protonation, see: (a) Duhamel, L.; Duhamel, P.; Plaquevent, J.-C. Tetrahedron: Asymmetry 2004, 15, 3653-3691.
2. (b) Yanagisawa, A.; Yamamoto, H. In Comprehensive Asymmetric Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer: New York, 1999; Vol. 3. pp 1295-1306.
3. (c) Yanagisawa, A.; Yamamoto, H. In Comprehensive Asymmetric Catalysis; Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds.; Springer: New York, 2004; Supplement 2. pp 125-132.
4. (d) Fehr, C. Angew. Chem., Int. Ed. Engl. 1996, 35, 2566-2587.
5. Behenna, D. C.; Stoltz, B. M. J. Am. Chem. Soc. 2004, 126, 15044-15045.
6. Mohr, J. T.; Behenna, D. C.; Harned, A. M.; Stoltz, B. M. Angew. Chem., Int. Ed. 2005, 44, 6924-6927.
7. For the development of phosphinooxazoline ligands, see: (a) Helmchen, G.; Pfaltz, A. Acc. Chem. Res. 2000, 33, 336-345.
8. (b) Williams, J. M. J. Synlett 1996. 705-710 and references therein.
9. A nonenantioselective decarboxylative protonation has been reported by Tsuji, see: (a) Tsuji, J.; Nisar, M.; Shimizu, I. J. Org. Chem. 1985, 50, 3416-3417.
10. (b) Mandai, T.; Imaji, M.; Takada, H.; Kawata, M.; Nokami, J.; Tsuji, J. J. Org. Chem. 1989, 54, 5395-5397.
11. To our knowledge, there are three other groups that have reported related Pd-catalyzed systems that produce similar enantioenriched products, sec: (a) Hénin, F.; Muzart, J. Tetrahedron: Asymmetry 1992, 3, 1161-1164.
12. (b) Aboulhoda, S. J.; Hénin, F.; Muzart, J.; Thorey, C.; Behnen, W.; Martens, J.; Mehler, T. Tetrahedron: Asymmetry 1994, 5, 1321-1326.
13. (c) Aboulhoda, S. J.; Létinois, S.; Wilken, J.; Reiners, I.; Hénin, F., Martens, J.; Muzart, J. Tetrahedron: Asymmetry 1995, 6, 1865-1868.
14. (d) Baur, M. A.; Riahi, A.; Hénin, F.; Muzart, J. Tetrahedron: Asymmetry 2003, 14, 2755-2761.
15. (e) Sugiura, M.; Nakai, T. Anqew. Chem., Int. Ed. Engl. 1997, 36, 2366-2368.
16. (f) Hamashima, Y.; Somei, H.; Shimura, Y.; Tamura, T.; Sodeoka, M. Org. Lett. 2004, 6, 1861-1864.
17. See the Supporting Information for details.
18. 7 The detailed mechanism of proton incorporation (e.g., proton transfer, reductive elimination, or otherwise) remains unclear and is under investigation.
19. We were interested in whether the other enolate precursors we have employed for enantioselective allylation chemistry would be competent substrates for the protonation reaction. To investigate this possibility, allyl enol carbonate i was subjected to our optimized reaction conditions for the formation of 5. Contrasting the result when (±)-2 was used (Table 2, entry 1), in this case, 5 was produced in 74% ee with a 66/44 ratio of 5/4 on a 0.1 mmol scale (100% conversion). When enol silane ii was used, low conversion (<5%) was observed, however, the ee of isolated 5 was 84%. While these results highlight the advantage of β ketoester precursors to the reactive enolate intermediate, it is uncertain why the reactivity and selectivity of these substrates is so different. The mechanism of this process is currently under investigation. (Diagram presented).
20. We recently completed the first asymmetric synthesis of (+)-dichroanone using our catalytic enantioselective Tsuji allylation, see; McFadden, R. M.; Stoltz, B. M. J. Am. Chem. Soc. 2006, 128, 7738-7739.